问题
填空题
已知a+3b与7a-5b垂直，且a-4b与7a-2b垂直，则<a，b>=（ ）。
答案
60°
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已知a+3b与7a-5b垂直，且a-4b与7a-2b垂直，则<a，b>=（ ）。
60°
| 阅读理解。 |
| My name is Mike Smith. I am twelve. I am an American boy. I have a sister. Her name is Kate. She's four. She's a pretty little girl. My father and mother are teachers. They love their work. They love their students, too. They work very hard. We have a house with a garden. The house is big and beautiful. The garden is small and nice. We often play there. We like our family. |
| 1. Mike is from ______. |
[ ] |
| A. America B. Canada C. England D. China |
| 2. Mr. and Mrs. Smith have ______ children. |
[ ] |
| A. four B. one C. three D. two |
| 3. Mike's sister is ______ years old. |
[ ] |
| A. two B. three C. four D. five |
| 4. What does Mrs. Smith do? She is ______. |
[ ] |
| A. a worker B. a teacher C. a student D. a doctor |
| 5. How is Mike's house? |
[ ] |
| A. The house is big. B. The house is nice. C. The house has a nice garden. D. A, B and C. |